Currently, surgeons will take approximately six x-rays of a patient's spine during both a pre-operative visit, as well as, at least three post-operation visits in order to determine spinal motion. These x-rays are not cost efficient for the patient, as the total is about $2000 per visit. The exposure to radiation is also harmful for the patient, as it is 60 mrem per x-ray. Each x-ray taken is time consuming and requires the patient to stand still while the series of x-rays are taken during each visit. Alternative apparatus and techniques for measuring spinal motion without the use of x-rays are therefore desirable.